Endoscope apparatuses having an endoscope, a light source apparatus, and so on have conventionally been widely used in the medical field and the like. In particular, endoscope apparatuses used in the medical field are mainly used for the purpose of allowing a user to perform treatments such as inspection and observation of the inside of a living body. Generally known observations using the endoscope apparatus in the medical field include, for example, normal observation, in which white light is irradiated into a living body to pick up an image of the inside of the living body which is generally the same as in naked-eye observation, and additionally thereto, fluorescent light observation, in which excitation light including a specific wavelength band is irradiated into a living body to pick up an image of auto-fluorescent light emitted by biological tissues in the living body, the auto-fluorescent light image being observed to determine a normal region and a lesion region in the living body.
In general, when performing a treatment such as inspection and observation with an endoscope, white balance adjustments respectively supporting observation modes of the endoscope apparatus are performed before the observation in order to adjust variation in color reproduction due to variations such as in sensitivity of a solid-state image pickup device in the endoscope, in optical characteristics of filter, lens or the like of a light source apparatus, and in chromatic aberration when the endoscope and the light source apparatus are connected to each other. For example, even in the case of performing treatments such as inspection and observation using endoscope apparatuses that are proposed in Japanese unexamined patent publications Nos. 11-089789 and 10-201707, before each observation, there are performed white balance adjustment as one of color balance adjustments, which is performed by picking up an image of a subject for normal observation, and color balance adjustment which is performed by picking up an image of a subject for fluorescent light observation.
The subjects used for the color balance adjustments including the above-mentioned white balance adjustment include, for example, one having a fluorescent member as a fluorescent light generating portion that emits fluorescent light by light. Of the above-mentioned subjects used for the color balance adjustments including the white balance adjustment, especially those having the fluorescent member are easily subjected to characteristic variations that occur in manufacture, such as, for example, variation in intensity of fluorescent light emitted by the fluorescent member.
It is desirable that the color balance adjustments supporting the observation modes of the endoscope apparatus, which are performed before each observation with the endoscope apparatus, are performed taking into consideration characteristic variation of the subject used for the color balance adjustment, in addition to the above-mentioned characteristic variation at each part of the endoscope apparatus.
However, in a fluorescent imaging apparatus of Japanese unexamined patent publication No. 11-089789 and an endoscope apparatus of Japanese unexamined patent publication No. 10-201707, no consideration is taken for characteristic variation of the subject that is used for white balance adjustment being performed, resulting in a problem that it is difficult to obtain a good observation image.
The present invention has been made in view of the above, and an object of the present invention is to provide an image processing apparatus, an endoscope apparatus, and a color balance adjusting method capable of obtaining a good observation image.